I have gone through all the posts here and thanks to all that posted items regarding inconsistent temperatures (hot air) from the different vents. I noticed posts on blend doors maybe causing the problem or perhaps the anti-freeze was not at the proper level. I noticed on cold mornings it would take forever to warm the cabin and as I started investigating, I would find that some vents were cold and others were warm. Seemed like left side was colder than the right side. I had the coolant flushed by Jiffy Lube since they have the vacuum system - definitely made a big difference but did not seem hot. Fellow Jeep owners say that it would be difficult to keep your hand in front of the vent if it is blowing right. I decided to replace the heater core. There are some great videos on how to do this - cutting the frame behind the glove box. Cutting the tubes of the heater core and using 5/8 heater hose - which allows for replacement in the future. After replacing and getting topped off, all is working great. All vents are blowing hot under full heat and it is nice to have to blend in cool air. Thanks again for all that posted. My jeep is a 2011 wrangler unlimited with 120k - i think that was the first heater core replacement based upon the core I removed.